DTC 17, High Resolution Circuit Fault: Notes

Optical sensor provides a high resolution signal to PCM by counting pulses on sensor disk located in injection pump. High resolution signal is one of the most important inputs used by PCM for fuel control and timing. DTC 17 will set when 8 pump cam reference pulses occur without an increase in high resolution counts (internal to PCM). PCM will default to backup fuel.

1. This step determines if a 5-volt reference is present.
2. This step checks ground circuit.
3. This step checks if sensor is sending a signal back to PCM.